1. Technical Field
The present invention relates to a plant endophytic microorganism and a microorganism formulation containing the same, and more particularly, to a novel microorganism Bacillus oryzicola and a microorganism formulation containing the same.
The present invention has been deduced from studies executed as a part of: the ‘Next-Generation Biopesticide Development Project’ (Project File No. 10044909, Project Title: Development of next-generation microorganism material for plant disease control using antagonist microorganisms) supported by the Ministry for Food, Agriculture, Forestry and Fisheries in 2010 and the ‘Industrial Convergence Core Technology Development Project’ supported by the Ministry of Industry and Trade in 2013 (Project File No. 808015-3-2, Project Title: Development of broad spectrum probiotic crop protective agent having sustained effects (2010-2013).
2. Background Art
Over the last few decades around the world, in order to increase a quantity of agricultural crops such as grains, greens, fruits, etc., a great amount of chemical fertilizer and agricultural pesticides for control of disease and insect pests, and weed control, have been used. Due to such a continuous use of chemical fertilizer and agricultural pesticides, some problems such as soil acidification, loss of soil fertility, environmental contamination, ecocide, mammal toxicity, causing pesticide resistance of disease and insect pests and weeds, or the like, have been consistently raised. Further, due to an abnormal climate change caused by an increase in amount of atmospheric carbon dioxide, continuous drought and salt accumulation in agricultural lands are now endangering stable production of agricultural crops.
In order to overcome the above-described problems, efforts for reducing amounts of used chemical fertilizer and agricultural pesticides have been made at home and abroad, and in particular, since the Act on the Support of Environmentally-friendly Agriculture was originally established in 1999, Korean policy has been carried now forward a third environmentally-friendly agriculture promotion. The goal of this plan is to accomplish a reduction in amounts of used chemical fertilizer and agricultural pesticides by about 15% till 2015, compared to 2011. At the same time, as a national requirement for safe foodstuffs is increasing due to an elevated living level in a social aspect, and eco-friendly agricultures such as an organic agriculture or natural agriculture oriented to the preservation of environment for agricultural production and natural ecosystem are rapidly expanding, such that studies on development of novel fertilizer and biological pesticides using microorganisms able to replace existing chemical fertilizer and pesticides are also rapidly increased. Multinational companies having well known the limitations in using the chemical fertilizer and pesticides, have recently developed and distributed biological agents, that is, plant activity enhancing agents able to compensate the above limitations. On the other hand, the multinational companies have conducted a seed development of drought-resistant crops possible to grow and develop even in some regions with serious drought or salt accumulation. Such developed microorganism products are formulated by selecting microorganisms having specific functions from the natural environment, and mass-culturing the same. The formulated microorganism products may be used for foliar spray or as a granular agent for soil treatment to prevent disease and insect pests, or otherwise, may also be used as the microorganism fertilizer or plant enhancing agent (see Non-Patent Document 1).
The microorganisms used herein are widely distributed in the natural environment such as soil, plant rhizosphere, ocean, etc., and have diversity in species and secrete different types of metabolites, thereby being effectively used in the environmentally-ecofriendly agriculture. Using the microorganisms may be generally classified into three types, including: directly using the microorganism itself; using metabolites produced by microbiologic fermentation; and using microorganism metabolites as a leading compound for novel synthesis of pesticides, or the like. Among these, the most used method is to directly use antagonistic microorganisms able to inhibit plant pathogens, plant growth promoting rhizobacteria (PGPR) and endophytic microorganisms to promote plant growth. In particular, studies on plant disease-resistance by these microorganisms have been greatly conducted.
Among diverse microorganisms, studies on endophytic bacteria have been actively made at the home and abroad in recent 10 years. Herein, the endophytic bacteria are defined as bacteria present in a tissue of a healthy and living plant to provide various advantages without any substantial harm to the plant. In general, it is known that the endophytic bacteria may be present in a space between plant cells or inside the cells, directly or indirectly induce resistance to disease, insect pests and stress, and have a great influence upon the growth of the plant. More particularly, it is presumed that the endophytic bacteria induce nitrogen fixation, solubilization of phosphoric acid, siderophore production, generation of active hormone, production of an antibacterial material or disease resistance of the plant, thereby preventing pathogenic infection and promoting plant growth (see Non-Patent Documents 1 to 4). Such endophytic bacteria are affinitive to a host plant and may form a symbiotic relationship in the tissue of the host plant without being recognized as the pathogenic bacteria, (see Non-Patent Document 5). Some specific endophytic bacteria may provide plant growth promoting effect and disease control effect by simultaneously using one or more mechanisms. Otherwise, different mechanisms may be applied during different periods in the life of plant. A plant gene may be changed by the presence of bacteria, and such changed gene may occasionally leave a clue to effects of the endophytic bacteria in the plant (see Non-Patent Document 6). The endophytic bacteria are proliferated inside the cells, wherein an entire density of the bacteria is high in a root and a beginning part of a stem, and is gradually reduced toward higher parts of the plant such as stems, leaves, etc. In a case of a corn leaf, it has been found that the density of the bacteria ranged from about 1×103 to 1×107 cfu/g. As the endophytic bacteria isolated up to now, about 130 species in about 50 genera including, for example, Bacillus, Pseudomonas, Enterobacter, Agrobacterium, or the like, have been discovered. These bacteria could assist the growth of economically important crops such as tomato, potato, corn and rice while suppressing an attack of diseases, thereby increasing the production of crops.
The rice is one of the top five crops in the world but involves production loss due to diverse diseases. Among these, a damage caused by pathogenic fungi such as rice blast, rice sheath blight, etc. incurred a fatal loss in crop production, and therefore, has been effectively prevented by developing resistant cultivars and developing chemical pesticides up to now. However, a bakanae, grain rot and bacterial blight, etc. of bacterial diseases, which are caused by seed transmission bacterial diseases, other than the above diseases also occur very often in some regions and cause a great damage. In recent years, these diseases have been difficult in their control. These pathogens overwinter in a rice paddy or the tissue of surrounding weeds, and in particular, since the rice is vulnerable to the pathogens under warm and moist conditions, it is difficult to control the disease if the disease starts to develop once. The control of the pathogens generally depends on chemical pesticides, however, using most of such chemical pesticides has incurred problems such as environmental contamination or mammal toxicity. Therefore, there is a growing interest in eco-friendly biological pesticides capable of replacing the above chemical pesticides.
Several tens species of biological pesticides for prevention of plant disease have been currently developed and commercially available in the internal and external markets. Among these, some effective biological pesticides are mostly manufactured using bacteria Bacillus and fungi such as Trichoderma (see Non-Patent Documents 7 to 10). Bacillus type products may include B. subtilis, B. pumilus and B. amyloliquefaciens, and most of these strains are known to have a mechanism of secreting an antibiotic material, that is, cyclic peptide such as iturin, surfactin, etc., to directly inhibit the pathogen, otherwise, to induce disease-resistance of the host. Bacillus sp. forms endospores and is survived for a long period of time even under poor natural environments, and because of quite high antibacterial ability, many researchers have investigated and published results thereof in regard to biological control of plant diseases (see Non-Patent Document 10). Other than those mentioned above, some results of studying novel endophytic bacteria, that is, Bacillus methylotropicus have recently reported. This strain was firstly isolated and defined with a nomenclature in Korea in 2010, and has been identified to have plant growth promoting ability (see Non-Patent Document 1). Following this, the above bacteria was isolated from ginseng, tomato and potato rhizospheres and reported to have pathogen inhibitory ability and plant growth promoting effect in China (see Non-Patent Documents 11 to 13). However, these studies do not include results in regard to induction of disease-resistance of the host plant or inhibition of other diseases, other than the antibacterial ability of the above strain to the plant pathogens. Studies on the endophytic microorganisms of rice have been mostly made by researchers in cultivation areas of rice, that is, Korea, China, etc., and researches into the comparison of a rhizospheric bacteria colony with latest practical and no-till paddy rice in each growth time period have been published. According to such research results, it was reported that the bacteria colony belonging to Proteobacteria were more found in the no-till paddy rice, while diverse bacteria belonging to Firmicutes, in particular, Bacillus sp. have been discovered in a relatively high ratio in a rice rhizosphere according to the practical agriculture (see Non-Patent Document 14). Further, it was reported that various species of Bacillus sp., Paenibacillus sp. and Pseudomonas sp., which inhibit the growth of pathogens such as rice blast or bakanae, have been isolated from the rice rhizospheres (see Non-Patent Document 15). Although such studies on diversity of different bacteria species living in the rice rhizosphere have been partially conducted, a research into novel bacteria having different functions while specifically acting on the rice as proposed in the present invention is still not disclosed. Besides, much researches have been done on the types of Bacillus sp. isolated from specific environments, however, only a few species thereof have been commercialized and are now effectively used for the plant control (see Non-Patent Documents 16 and 17). One reason of this fact is presumed that the pest control effect may be relatively low because a mechanism for inhibiting pathogens only was adopted as a standard when isolating the antagonist bacteria. Accordingly, in order to more effectively prevent a disease while expressing characteristics of the above strain, it is necessary to investigate and develop novel multi-functional microorganisms able to simultaneously endow an ability of inducing disease-resistance of the host plant and effects of promoting a growth of the host plant, thereby enhancing the host plant.